Center for the Built Environment

We evaluate the heat transfer from radiant ceilings that have suspended acoustical panels present for noise reduction. An upward-directed ceiling fan is added to offset the reduction of heat exchange due to the acoustical panels. We systematically simulate the indoor thermal environment and the changes to heat transfer coefficients caused by the interaction between radiant ceiling panels, acoustical panels, and ceiling fan under four influencing factors: (1) coverage ratio of acoustical panels, (2) fan rotational speed, (3) radiation panel temperature and (4) room height. The simulation method is validated with experimental data. Numerical results show that the augmented air speed increases convective and total heat transfer for radiant panel. Simulated temperature non-uniformity, air and operative temperature in the occupied part of the room is reduced with increased fan speed, and with decreased acoustical panel coverage ratio. The PMV increased with increased acoustical panel coverage ratio and radiant surface temperature, and also with reduced fan speed. When using fans, the radiant surface temperature can be raised 2 ℃ while maintaining equivalent thermal comfort, allowing higher water supply temperatures. The radiation heat transfer coefficient of the bare ceiling is decreased 25% by adding 63% acoustical panel coverage. The total heat transfer coefficient of radiant ceiling increases with fan speed up to 106.2% over a no-fan base case, and decreases with increased acoustical panel coverage ratio. The study indicates that an upward-directed ceiling fan is a worthwhile method to enable raised radiant surface temperatures, save cooling energy, and reduce surface condensation risk.